使用动态代理解决全局乱码问题

Posted 2020-10-24 jepson6669

package www.test.web.filter;

import java.io.IOException;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;

public class EncodingFilter implements Filter{

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
    }

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
            throws IOException, ServletException {
        final HttpServletRequest req = (HttpServletRequest) request;
        //使用动态代码解决全局乱码问题
        HttpServletRequest enhanceRequset = (HttpServletRequest) Proxy.newProxyInstance(
            //loader ,和目标类相同的类加载器
            request.getClass().getClassLoader(),
            // interfaces  :代表与目标对象实现的所有接口字节码对象数组
            request.getClass().getInterfaces(),
            
            // h : 具体的操作，InvocationHandler接口
            new InvocationHandler() {
                
                @Override
                public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
                    //对 getParameter 方法进行增强
                    String name = method.getName();//获得目标对象的方法名称
                    if("getParameter".equals(name)){
                        String invoke = (String) method.invoke(req, args);//乱码
                        //转码
                        invoke = new String(invoke.getBytes("iso8859-1"),"UTF-8");
                        return invoke;
                        } 
                    return method.invoke(req, args);
                }
            });
        chain.doFilter(enhanceRequset, response);
    }

    @Override
    public void destroy() {
    }
    
}

动态代理：实际开发中一般用于拦截。判断不同的角色，决定是否可以调用这个方法。